Frequency and time domain studies of the micro-EEG from the brain extracellular space

In these studies, recordings from the brain extracellular space of cats are considered. Macro and microelectrodes are utilized. Special studies using visual, auditory stimuli and certain drugs are done. Coherence, power phase and partial coherence spectra of wave field potentials and unit potentials are investigated. The electrographic profile of the micro electroencephalogram (EEG) and micro evoked response (ER) of the extracellular space is different than the macropotentials of the macro (EEG) and the macro (ER). The electrographic patterns of the micro (EEG) and the micro (ER) will vary with the microelectrode size, location and the variable microanatomy. There are many single neuron field potentials differentiated in space and time. In these unit fields there are varying electronic interactions varying in space and time. There are patterned inputs varying in space and time. There are fluctuating microfields distributed in overlapping layers, columns, slabs and patches and periaxonal extracellular spaces of the cerebral and cerebellar white matter. In these anatomical situations there are variable, degrees of local and general selective patterns of synchronization with variable direction, and selective spread. The extracellular space micro (EEG) shows complex and dynamic shifts of the micro (EEG) to the macro (EEG) frequencies and tuned macrofields.